With increasing down-scaling of semiconductor devices, various processing techniques, such as photolithography, have been adapted to allow for the manufacture of devices with increasingly smaller dimensions; however, as semiconductor processes require smaller process windows, the manufacture of these devices have approached and even surpassed theoretical limits of conventional photolithography techniques. As semiconductor devices continue to shrink, the desired spacing between elements of a device may be less than the pitch that can be manufactured using traditional optical masks and lithography techniques.
Next generation lithography (NGL) is expected to replace current optical lithography methods. There are several NGL candidates, such as extreme ultraviolet (EUV) lithography (EUVL), electron projection lithography (EPL), ion projection lithography (IPL), nanoimprint, and X-ray lithography. Of these, EUVL is an attractive candidate—having most of the properties of optical lithography.